Thermostatic circuit breaker sensitive to several temperatures



March 10,1970

v A. NARDULLI 3,500,277

THERMOSTATI EC CIRCUIT BREAKER SENSITIVE TO SEVERAL TEMPERATURES Filed Jan. 2, 1968 BIMETA I.

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1 HII x Inven Antonio Nardu i.

United States Patent 6 3,500,277 THERMOSTATIC CIRCUIT BREAKER SENSITIVE T SEVERAL TEMPERATURES Antonio Nardulli, Marigliano, Naples, Italy, assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed Jan. 2, 1968, Ser. No. 694,945 Claims priority, application Italy, July 25, 1967, 38,411/67 Int. Cl. H01h 37/74 US. Cl. 337343 3 Claims ABSTRACT OF THE DISCLOSURE A thermostatic circuit breaker responsive to two temperatures comprising a first and a second snap acting thermostatic discs, the second disc having an opening in the center through which extends a control element between the first disc and a first switch mechanism; and a second control element coaxial with the first control element extending between the central portion of the second disc and a second switching mechanism. The thermostatic discs are chosen so that they snap to their reverse curvature at different temperatures.

The switching mechanisms are supported in a case and a thermally conductive cap, exposed to the ambient, is placed on a seat provided therein. The cap is shaped to form two annular platforms of differing diameters. The two discs are sized so that the periphery of each fits on a respective platform. The disc closest to the case has an opening in its center through which a first rod of insulating material is slidably mounted between the disc furthest from the case and a movable contact arm of a first switch. The rod also extends through an opening in the movable contact arm of a second switch. A second rod, a tubular element of insulating material, is slidably mounted axially on the first rod between the central portion of the disc nearest the case and the movable contact arm of the second switch. The two switches can be normally opened or closed but upon snapping of the discs the rods are mov :d thereby moving the movable contact arm of the switch es. Thus the switches, with their respective disc and control rod, are functionally independent of one another.

BACKGROUND OF THE INVENTION The invention relates to a thermostatic circuit breaker sensitive to two or more temperatures.

According to the present invention a thermostatic circuit breaker sensitive to two temperatures is provided comprising a case inside of which are contained a first and a second calotte-type bimetallic element, the second bimetallic element having a centrally located aperture so as to permit the passage of a first motion transfer rod supported on the center of the first bimetallic element; a second motion transfer rod coaxial with the first rod and supported by the central zone of the second bimetallic element; the first and second bimetallic elements being so disposed as to actuate independent contacts in accordance with the reversal of the curvature of the first and/ or second bimetallic elements at the respective snapover temperatures.

In the accompanying drawings, one of the various possible embodiments of the invention is illustrated.

The figure shows in cross section the thermostatic device sensitive to two temperatures according to the invention.

As can be seen from the figure the thermostatic device according to the invention comprises a case 1 containing 3,500,277 Patented Mar. 10, 1970 a seat 2 on which is disposed a metallic cap 3 which is in contact with the atmosphere of the surrounding medium in which variations of temperature take place.

The metallic cap 3 is shaped so as to present two plane seats in the form of an annular platform 4-5 on which the periphery of the bimetallic disks 6-7 are loosely supported.

The bimetallic disk 6 is formed in such a way that its curvature reverses itself upon a predetermined temperature condition T1.

The bimetallic disk 7 has a centrally located aperture and is formed so that its curvature reverses itself upon a predetermined temperature condition T2.

A motion transfer rod 8 of insulating material is supported near the center of bimetallic disc 6, sliding inside the bore of another motion transfer rod 9 passing through the apertures in the disk 7 and in the movable contact arm 14 and contacting the movable contact arm 10.

The contact arm 10 is adapted to move toward and away from the stationary contact arm 11.

The contact arms 10 and 11 are then connected respectively to the anchorage terminals 12 and 13.

The motion transfer rod 9 extends between movable contact arm 14 and disc 7 and slides axially under the influence of the arm 14 and disc 7.

The contact arm 14 is adapted to move toward and away from the stationary contact 15.

The contact arms 14 and 15 are then connected respectively with the anchorage terminals 16 and 17.

As seen in the drawing, the elongated movable contact arms 10 and 14 extend in generally parallel, opposite directions.

In the normal operation of the device, the cap 3 is in contact with the element (liquid, solid or gaseous) whose temperature it is desired to control. Through the metallic cap the heat is transferred to the thermally sensitive elements 4 and 5.

At an increase of the temperature when the disk 6 reaches the snap-over temperature, it reverses its curvature, moving toward the upper motion transfer rod 8 which opens or closes the circuit established by the contacts mounted on arms 10 and 11.

A preselected circuit connected in series to the terminals 12 and 13 makes it therefore possible to stabilize the temperature to the value T If, instead, the preselected circuit is arranged between the terminals 16 and 17 then, at the temperature T the disk 4 will snap over without causing any relative movement between the contacts mounted on arms 14 and 15.

When at the snap-over temperature T of the disk 5 the reversal of the curvature transfers through the motion transfer rod 9 it will open or close the circuit formed by the contacts mounted on arms 14 and 15.

The temperature will therefore be stabilized at the value T In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense.

3 Iclaim: 1. A thermostatic switch responsive to two different temperatures comprising:

a base of electrically insulating material and having a bore therein;

a first motion transfer rod slidable in the bore, the first rod having an axially extending concentric bore therethrough;

a second motion transfer rod slidable in the bore of the first rod and longer than the first rod;

a thermally-conductive cap received on the base covering one end of the bore in the base, the cap being formed with a first and second annular platform, each platform forming a plane perpendicular to the axis of the bores and spaced apart along the extended axis of the bores;

a first thermostatic disc movable from one curvature to an opposite curvature upon occurrence of a predetermined temperature condition, the periphery of the first disc loosely supported on the first annular platform;

a second thermostatic disc movable from one curvature to an opposite curvature upon the occurrence of a predetermined temperature condition different from that of the first disc and having a centrally located aperture therein, the periphery of the second disc loosely supported on the second annular platform;

a first stationary contact arm and a first elongated, flexible, movable contact arm mounted on the base,

the first movable contact arm movable toward and away from the first stationary contact arm; and

a second elongated, flexible, movable contact arm mounted on the base, the second movable contact arm movable toward and away from the second stationary contact arm, the first rod extending from the first disc to the first movable contact, the second rod extending from the second disc through the aperture in the first disc to the second movable contact arm.

2. A switch as defined in claim 1 in which the first and second movable arms extend in generally parallel, opposite directions, the first movable arm having an aperture therein and the second rod extends through the aperture in the first movable arm.

3. A switch as defined in claim 2 in which the first movable contact arm is biased against the first stationary contact arm and the second movable contact arm is biased against the second stationary contact arm.

References Cited UNITED STATES PATENTS 7/1940 Vaughan et a1. 33788 4/1951 Burkholder 337-3 US. Cl. X.R. 337-3, 88 

